When placing work products in a shipping container, it is desirable to place several work products at a time in the container and, in some instances, the work products must be collected in a desired pattern of the products for fitting into the container of a specific size and shape.
For example, in the bakery industry a producer typically will produce several sizes of loaves of bread and has one type of shipping container in which the products are to be packed and shipped. Because different ones of the products may be different in size and shape from time to time, the products may fit best in the shipping container when the products are configured in different arrangements, or “pack patterns,” than other sized products. The pack patterns may be dependent upon the product sizes.
A robot may be used to pick the products up with multiple picks of the end effector at various positions of the end effector to form the desired pack pattern for the particular shipping container. The robot then places the products into the shipping container all at once, in the desired pattern.
The end effector that is used to pick and place products typically will use multiple suction cups that are used as vacuum retrievers to provide the seal between the vacuum source and the objects being picked. When multiple picks are required for one delivery of the products to the shipping container, the vacuum must be applied to certain ones of the suction cups on the end effector to enable picking or holding the product in that pick zone while the other zones of the suction surface must not allow vacuum flow because those zones of the end effector are not yet covered by work products. To accomplish this, the vacuum source may be applied in several suction cups, and the suction cups are then applied to the work product. The suction cups that are not in communication with the vacuum source cannot pick the work products in that picking zone.
It is desirable to have the end effector in a compact, low profile and to employ the smallest number of components necessary for the end effector to achieve its functions.
Usually, a single vacuum source is applied to the end effector, and the end effector controls the application of the subatmospheric pressure to the suction cups.
Additional information concerning end effectors for robots may be found in U.S. Pat. No. 7,950,708. The disclosure in said patent concerning programmable zoned end effectors is adopted herein in its entirety by reference.
End effectors having vacuum charged suction cups may be used to pick and place work products that have loose outer coverings, such as loaves of sliced bread in a plastic bag, so that when the vacuum of a suction cup is applied to the work product, it tends to lift the plastic bag and the plastic bag, in turn, lifts the product inside the plastic bag. This generally tends to separate the upper portion of the plastic bag from the work product, causing a portion of the plastic bag to be lifted up to the interior of the suction cup. This is not desirable in that it sometimes stretches the plastic bags and may even rupture the plastic bags while the work product is attached to the end effector. Also, the shreds of plastic and film that are separated from the plastic bags during the application of the vacuum to the bags tends to move into the suction cup, through the air flow system, including the valves, the low pressure air plenum, etc., requiring these and other components of the equipment to be cleaned so as to maintain the function and durability of the component parts of the system.